A malfunctioning burner in an oil-fired heating device, such as an oil-fired furnace, can lead to inefficient and unsafe conditions. For example, a burner receiving an incorrect air/fuel mixture can result in improper combustion, causing a high level of smoke (soot) to be generated during operation. Over time, the soot builds up in the furnace system, clogging the heat exchange passageways. Clogged heat exchange passageways result in the furnace having to be operated for a longer period of time and/or at a higher temperature for adequate heating, which is inefficient. Expensive and time-consuming maintenance must then be performed to remove the soot build-up. Further, in some instances, the soot produced will exit the furnace system and be dispersed throughout a home. The damage can be quite extensive and extremely costly to clean up.
Soot build-up in the furnace system can also limit the oxygen supply to the burner. This leads to incomplete combustion of the oil and, as a result, the production of carbon monoxide gas. Carbon monoxide gas is a serious safety concern.
Techniques have been devised to detect smoke being produced by a furnace and, upon detection of smoke, turn off the furnace. See, for example, U.S. Pat. No. 4,171,944 issued to Hirschmann, entitled “Combined Smoke Detection and Furnace Shut Off Device” (hereinafter “Hirschmann”). In Hirschmann, a smoke detector is placed in a room near the furnace. In the event that smoke is detected in the room, the smoke detector causes ignition within the furnace to be stopped. While the device in Hirschmann may be applicable to extreme smoke conditions, such as when there is a furnace fire, the device would not function to detect the level of smoke produced by a malfunctioning burner. Specifically, since the detector in Hirschmann is external to the furnace system, the smoke from a malfunctioning burner would likely not even be detected.
In U.S. Pat. No. 2,727,203 issued to Zeitlin et al., entitled “Smoke Detector and Blower Motor Control System” (hereinafter “Zeitlin”), a light source, namely a light bulb, and a photo-cell are placed in a chimney to detect smoke. When smoke is detected, a burner shut-off mechanism is activated. The device described in Zeitlin, however, would not provide the level of sensitivity needed to detect smoke produced by a malfunctioning burner. Further, furnaces of different designs and of different ages, during normal operations, produce different acceptable amounts of smoke. The device described in Zeitlin would not accommodate those variations.
Thus, there exists a need for improved techniques to prevent excessive smoke conditions within systems, such as a furnace system.